Conceived, developed and produced by Audemars Piguet, the new hand-wound Calibre 2910 driving the Millenary Minute Repeater is also distinguished by the atypical construction of the regulating organ. The latter is composed, not of one balance- spring, but of two balance-springs placed top to tail. This flat opposite-facing double balance-spring system boasts numerous advantages: it ensures automatic compensation for potential poising flaws; eliminates the need for the “overcoil” terminal curves of so-called “Breguet-type” balance-springs, which are always very tricky to make; and also does away with the imprecision resulting from the vertical position of the watch without needing to resort to such a sophisticated device as the tourbillon. All these special features serve to ensure finer adjustment of the balance- and-spring assembly oscillating at a frequency of 21,600 vibrations per hour. The two movement barrels guarantee an exceptional seven-day power reserve. A third barrel dedicated to the striking mechanism is two and a half times larger than normal, and enhances the regularity of the note. Finally, in terms of security, the Millenary Minute Repeater is equipped with a balance-stop system designed to ensuring time- setting that is accurate to the nearest second. The new winding system also features a security device that prevents time-setting while the striking mechanism is in operation, thus avoiding any risk of inappropriate handling.